Glycol-free aqueous antifreeze compositions comprising dicarboxylic acid salts

Abstract

The present invention relates to an aqueous antifreeze composition comprising 10 to 50% by weight of one or more dicarboxylic acids, preferably aliphatic dicarboxylic acids having 4 to 12 carbon atoms in the form of the alkali metal, ammonium or alkaline earth metal salt. Preferably, these salts are used in combination with at least one further substance. This gives antifreeze compositions with a good frost protective action, good heat conductivity and good protection against corrosion.

1. An aqueous antifreeze composition comprising 10 to 50% by weight of one or more salts from the group of saturated and unsaturated, aliphatic and aromatic dicarboxylic acids being adipic acid and dodecandicarboxylic acid in the form of the alkali metal, ammonium or alkaline earth metal salt, further comprising one or more corrosion-inhibiting substances for aqueous coolants, and
 (a) 0.01 to 5% by weight p-hydroxybenzoic acid and 2-ethylhexanoic acid in the form of alkali metal, ammonium and substituted ammonium salts thereof. 
 
     
     
       2. An antifreeze composition as claimed in  claim 1 , wherein the salt is a sodium or potassium salt, an ammonium, trialkylamine or trialkanolamine salt. 
     
     
       3. An antifreeze composition as claimed in  claim 1 , which further comprises one or more compounds from the groups listed below
 b) 0.01 to 5% by weight of one or more compounds from the group of aliphatic and aromatic di- and tricarboxylic acids each having 3 to 21 carbon atoms other than those recited in  claim 1  in the form of their alkali metal, ammonium and substituted ammonium salts, where, in cases where a dicarboxylic acid is used, this is different from the dicarboxylic acid used as antifreeze composition. 
 c) 0 to 1% by weight of one or more compounds from the group of alkali metal borates, alkali metal phosphates, alkali metal silicates, alkali metal nitrites, alkali metal and alkaline earth metal nitrates, molybdates and alkali metal and alkaline earth metal fluorides; 
 d) 0 to 1 % by weight of one or more compounds from the group of hard-water stabilizers based on polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymers, polyvinylpyrrolidone, polyvinylimidazole, vinylpyrrolidone-vinylimidazole copolymers and copolymers of unsaturated carboxylic acids and olefins; 
 e) 0.01 to 5% by weight of one or more compounds from the group of carboxamides and sulfonamides; 
 f) 0.01 to 5% by weight of one or more compounds from the group of mono- and binuclear unsaturated and partially unsaturated heterocycles having 4 to 10 carbon atoms, which may be benzo-fused or carry additional functional groups, 
 g) 0.01 to 5% by weight of one or more compounds from the group of tetra(C 1 -C 8 -alkoxy)silanes (orthosilicic acid tetra-C 1 -C 8 -alkyl esters); and 
 h) 0.01 to 5% by weight of one or more compounds from the group of aliphatic, cycloaliphatic and aromatic amines having 2 to 15 carbon atoms which may additionally contain ether oxygen atoms or hydroxyl groups. 
 
     
     
       4. An antifreeze composition as claimed in  claim 3 , wherein the combination of one or more substances from the groups b), c), d) and/or f) is present. 
     
     
       5. An antifreeze composition as claimed in  claim 4 , wherein a combination of one or more substances from groups b), c) and f) is present, and wherein
 b) is sebacic acid or dodecanedicarboxylic acid, 
 c) is sodium molybdate or sodium metasilicate, and 
 f) is tolutriazole, benzotriazole of 1H-1,2,4-triazole. 
 
     
     
       6. An antifreeze composition as claimed in  claim 1 , wherein their pH is in the range from 6 to 11. 
     
     
       7. An antifreeze composition as claimed in  claim 1 , which comprises less than 10% by weight of ethylene glycol, propylene glycol, polyethylene glycols and/or polypropylene glycols having 2 to 15 glycol ether units.